This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Wells are frequently used to extract fluids, such as oil, gas, and water, from subterranean reserves. These fluids, however, are often expensive to extract because they naturally flow relatively slowly to the well bore. Frequently, a substantial portion of the fluid is separated from the well by bodies of rock and other solid materials. These solid formations impede fluid flow to the well and tend to reduce the well's rate of production.
This effect, however, can be mitigated with certain well-enhancement techniques. Well output often can be boosted by hydraulically fracturing the rock disposed near the bottom of the well, using a process referred to as “fracing.” To frac a well, a fracturing fluid is pumped into the well until the down-hole pressure rises, causing cracks to form in the surrounding rock. The fracturing fluid flows into the cracks and propagates them away from the well, toward more distant fluid reserves. To impede the cracks from closing after the fracing pressure is removed, the fracturing fluid typically carries a substance referred to as a proppant. The proppant is typically a solid, permeable material, such as sand, that remains in the cracks and holds them at least partially open after the fracturing pressure is released. The resulting porous passages provide a lower-resistance path for the extracted fluid to flow to the well bore, increasing the well's rate of production.
Fracing a well often produces pressures in the well that are greater than the pressure-rating of certain well components. For example, some wellheads are rated for pressures up to 5,000 psi, a rating which is often adequate for pressures naturally arising from the extracted fluid, but some fracing operations can produce pressures that are greater than 10,000 psi. Thus, there is a need to protect some wellhead components from fluid pressure arising from well fracing.